Grinding machine



May 30, 1933. w. F. FRASER GRINDING MACHINE Filed Oct. 1, 1928 4 Sheets-Sheet 1 WUZ'HO@ WARREN E FRASER W/TNEssEs AMaly 30, 1933. w. F. FRASER- GRINDING MACHINE Filed Oct. l, 1928 4 Sheets-Sheet 2 N .www

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May 3o, 1988.A w. F, rFRASER 1,911,889

GRINDING MACHINE Filed oct. .1, 1928 4 sheets-sheet 5 Mmm''liii I@ F 2? 222 /Fn gg 5 wuantoz WITNESSES A MRRENITFRHSER 0W 811 @im atto: 1w 11 Patented May 3o, 1933 UNITED .STATES PATENT OFFICE WARREN F. FRASER, OF WESTBORO, MASSACHUSETTS, ASSIGNOR TO NORTON COMPANY, l OF WORCESTER, MASSACHUSETTS, A CORPORATION OF MASSACHUSETTS GRINDING MACHINE Application med october 1, 192s. serial No. 309,521.

This invention relates to machines for precision grinding. Its object is to provide a machine for automatically grinding work pieces to size uniformly Within the closest possible limits.`

In the art to which this invention relates, grinding machines are employedwhich include feeding mechanism for relatively movextreme delicacy of control. On the other hand, to insure the accurate operation of the calipering mechanism this must be extremely light inits construction and must operate under light pressure. The area of surface of its contact points must be kept small in order to reduce the possibility of foreign matter being retained between the contacts andthe work and the pressure must be light to avoid marking the work, especially where it is not hardened. The conditions, therefore, under which the calipering mechanism best operates militate against'a powerful and positive controlling action.

With these conditions in mind, the present invention consists in calipering mechanism of novel construction wherein the calipering movement is utilized to trip a sensitive latch mechanism under conditions of light pressure and the tripping of the latch mechanism is taken advantage of in a novel manner to govern an.l actuating system which, in turn, is utilized to control the action of the feeding mechanism. As herein shown, the actuating system comprises an electric circuit. The controlling switch of this circuit is arranged to be closed manually-by the operator and this operation ener- -gizes a source of power which is subsequently utilized to effect automatically a sudden and wide break of the contact members of the switch when tripped by the calipering device. found it possible to maintain good electrical contact under adequate pressure during the grmding operation and vyet effectually to break this contact in response to an extremely slight and delicate movement of the caliper elements.

In this connection another feature of the invention consists in a calipering device in- By using this construction, I have' cluding a train of mechanism arranged to be latched under tension when contact is establlshed and having a trip acting at a point in the train remote from its point of connection with the contact member where an extremely light pressure is effective for locking the train. The calipering device is arranged to act upon the trip at this point inthey train and consequently a release of great nicety under conditions of light pressure is provided.

Other features of the invention relate to a novel feeding mechanism whereby the work and the grinding element may be moved toward and from eachother accurately and positively and at speeds appropriate for the different requirements. As herein shown, the grinding wheel is moved at high speed from a remote initial position into a preliminary grinding relation to the work, then fed into the work at a slow sneed i until a predetermined diameter is reached, then held at rest while a further slight reduction of diameter takes place and finally etracted at high speed to its'initial posiion.

c To accomplish these results, the present invention contemplates feeding mechanism including a plurality of clutches driven at different speeds and in diiferent directions, together with means for timing their action and throwing them successively into operation. Certain of these clutches are controlled through the action of the calipering device and others, such as that eective for producing the preliminary movement of the grinding wheel, are mechanically controlled.

It is believed that feeding mechanism including caliper controlled and mechanically Controlled driving clutches has never before been employed in machines for precision grinding.

These and other features of the invention will be best understood and appreciated from the following description of a preferred embodiment thereof, selected for purposes of lo illustration and shown in the accompanying drawings, in which Fig. 1 isa view in perspective showing somewhat diagrammatically the arrangement of the grinding wheel slide and its feeding mechanism, the work and the calipering device;

Fig. 2 is a view in elevation, partly 1n section, of the feeding mechanism; y

Fig. 3 is a plan view of the calipering .0 mechanism;

Fig. 4 is a sectional view on the line 4-4 of Fig. 2;

Fig. 5 is a sectional view of the calipering mechanism on the line 5 5 of Flg. 3;

Fig. 6 is a sectional view of Ythe ca lipering mechanism on the line of F1g.'5;

Fig. 7 is a view partly in section of a portion of the calipering mechanism on the line 7 7 of Figs. 5 and 8;

Fig. 8 is a view in end elevation of the switch mechanism with the casing in section; and

Fig. 9 is a diagram of the electric circuit.

In the cylinder grinding machine illustrated, the grinding wheel 100 is mounted on a driven shaft 102 journaled in a cross slide 104, suitably supported by transverse ways in the machine frame, not shown. In

40 the bottom of the grinding wheel slide 1s provided a half nut 106 which cooperates with a lead screw in the shaft l2 for moving the slide to carry the grinding wheel toward or from the work. The work piece to be ground is indicated by reference character 108 and is supportedupon centers, one of which'll() is shown in Fig. 1 and rotated while being ground. The mechanism thus far described is well-known in commercial grinding machines such, for example, as that shown in the patent to Norton No. 762,838. To move the grinding wheel 100 toward and from the rotating work, I prefer to employ mechanism which will now be described.. The lead screw shaft l2 carries a pinion 27 which meshes with another pinion 28 onthe rear end of a shaft 10which is journaled in bearings 11, shown inY Fig. 4, and all of which are carried by the machine frame. Rotation is transmitted to the lead screw shaft 12 through the shaft 10 which may be turned manually by a hand wheel 14 fast to its forward end or automatically and mechanically through a worm wheel 13 '5 which, in turn, is driven by a worm 25 on the left end of a. lead screw driving shaft 26', best shown in Fig. 2. The worm wheel 13 may be locked to the shaft or may be free toy rotate upon it according as it is desired to utilize the automatic feed or the manually controlled feed. To this enda gear 15 is rigidly secured to the worm wheel 13 and arranged to. mesh with a pinion 24 formed in the rear end of a plunger- 21 which is slidably mounted in a sleeve 16 to rotate therewith. y This sleeve 16, in turn, is rotatably mounted in the hand wheel 14. The sleeve. 16 has an integral arm carrying a locking in 17 adapted to enter4 one of a series of' oles 20 arranged circlunferentially in a disk formed on the hand wheel 14 and being maintained in locking position by a spring, shown in Fig. 4. The plunger 21 is keyed to the sleeve 16 so that it may be retracted when it is desired to disengage the hand wheel 14 from the automatic feedA mechanism.

It is desirable, for a purpose which will presently appear, to provide for changing by small amounts the angular relation of the worm Wheel 13 and the shaft 10 and this may be effected by withdrawing the pin 17 and rotating the sleeve 16 by its arm t`o turn the plunger 21 through the desired angle and then releasing the pin to lock the sleeve and plunger in adjusted p0- sition, as determined by one or another of the holes 2O.l

Provision is made for rotating the driving shaft 26 at two different speeds in a direction to advance the grinding wheel toward the work and at one speed in the reverse direction. To this end, a gear 30 having a cone'clutch face is loosely mounted upon the shaft.26 and arranged to be rotated at high speed in the direction of the arrow in Fig. 2, that is, forwardly at the top. This-gear is driven, through an intermediate gear 113, by a gear'112 on a shaft 114 carrying a pulley 116 'connected by a belt to any convenient source of power. A similar gear 32, having an oppositely disposed cone clutch surface, is also mounted upon the sha-ft 26 and this is arranged to be driven at a high speed in the opposite direction directly by a large gear 118 on the shaft 114. Between the clutch gears 30 and 32 vis disposed a sliding clutch member 36 having oppositely disposed annular clutch surfaces adapted t0 cooperate with those of either gear, depending uponl the. direction which it is desiredto'drive the shaft 26.

The clutch member 36 is arranged to be l at its outer end a set of change speed pulleys 124 adapted to be driven by a belt from any convenient source of power. A clutch member 40 is slidably keyed to a sleeve f 41 upon the shaft 26 and this may be shifted to engage or disengage the clutch gear 34, so that the sleeve 41 is rotated or not.

Rigidly secured to the shaft 26 is a flange 45 having a pawl 46 on its face which cooperates with a -ratchet 47 formed upon a tlange of the sleeve 41. The ratchet and pawl are so arranged that when the clutch4 member'40 is engaged with the clutch gear 34 and driven thereby the ratchet 47 will drive the shaft 26 in the same direction and at the same speed but it will at all times leave the shaft 26 free to be driven at a higher speed in the same direction by the clutch gear 32.

In order` to time the rotation of the worm wheel 13 and impart to it a definite cycle of movement of more than a single revolution, the following mechanism is provided. The shaft 26 carries another worm 48 which is arranged to drive a wormvwheel 49 rotatably mounted upon a stud 50. The design of the worm 48 and the worm wheel 49 is such that the worm wheel'is given a slower angular movement than the worm wheel 13, making less than a revolution while the worm wheel 13 is moved through-a number of revolutions sufficient to impart adequate movement'to the grinding wheel slide.

The worm wheel 49 carries a cam ring 51 having inclined faces 52 and 53. A. trip cam :54 is also provided upon the shaft 50 and this rotates in fixed relation with the cam ring 51. The worm Wheel49 also carries.

a ring 57 of insulating material having a conducting segment 58 adapted to contact with brushes 59 and 60 to close and maintain an electric Vcircuit through them for a definite interval.

site directions to shift the clutch member 36 by the cams already mentioned and by a solenoid controlled by the calipering mechanism. For this purpose, it is provided with an arm 61 to which is pivoted a vertically disposed rod 62. The rod is encircled by a compression spring 63, tending normally to lift the arm 61 and shift the clutch member into engagement with the clutch gear 30. The rod 62 is guided in its movement by a stationary bracket 64 and is connected at its lower end to the core 65 of a solenoid 66.

The arm 67 of the bell crank lever 42 is pivotally connected to a vertical rod 68 located directly behind the rod 62, as shown in Fig. 1. This rod 68 is provided with a compression spring which tends normally to lift the arm 67 and the rod passes also through the bracket 64. Below the bracket 64 it 1s connected to the core 69 of a solenoid'Q. -The arm 61 is provided with an extension 71 so located that when this arm is in .its extreme uppermost position and the vclutch member 36 is in engagement with the clutch, gear 30 the arm 67 cannot then be .lowered to shift the clutch member 40 into engagement with the clutch v are associated with the worm wheel 49. As vshown in Fig. 2 of the drawings, the shifter Y arm 37 has been swung by the solenoid 66 to engage the clutch member 39 with the clutch gear 32 so that the shaft 26 is being rotated at a lhigh speed in a direction to move the grinding wheel slide at high speed toward the Work. This action continues until the worm wheel 49 is rotated far enough to bring ythe cam face 52 into contact with the cam roller of the arm 72. When this occurs, the arm 72 is rocked positively downward in opposition to the pull of the solenoid 66, as willrbe presently explained, and the clutch member 36 is disengaged from the clutch gear 32. The same rotation of the worm wheel 49 has caused the segment 58 to close av circuit through the ..brushes 59 and 60, thereby energizing. the

solenoid 7 0 and swinging the shifting lever 42 to engage the clutch gear 34, which will continue rotation of the shaft 26 but at a slower speed to cause the slow feed of the grinding wheel into the work.

The construction of the calipering mechanism by which the solenoids are controlled will now be explained'. Ways 130 are provided on the machine frame for supporting the calipering mechanism, which is mounted The bell crank lever 37 is swung in oppoupon a bracket 132 shaped to it the ways and to be clamped in any desired position thereon by a clamping plate 134 which is bolted to the lower side of the bracket. The bracket 132 has a plane upper face and has a carrier member 136 pivotally mounted in its lower flange upon a pin 138. '.Pivotally mounted by a pin 300 in the upper end of the carrier member is a frame piece 140 which carries two forwardly extending bars 142 and 144. The bar 144, as shown in Figs. l and 3, is provided with a boss in which is mounted a spring plunger 146.

which bears upon the upper surface of the bracket 132 and urges the bars 142 and 144 and thevparts carried thereby upwardly to a position determined by the engagement of the lower caliper member with the bottom of the work. The plunger 146 is provided at its upper end with a stop nut which serves to limit the downward movement of the plunger and, consequently, the upward .l movement of the bar 144 when no work is intended to engage the work piece at a point .substantially opposite the grinding lpoint and to locate transversely the calipering mechanism. The -bracket member 150 also carries iu its lower end a vertically disposed contact screw 156 having a clamping screw 158, whichcontact screw 156 is designed to engage the bottom of the work piece, being pressed against it by the action of the spring plunger 146 above referred to.

Between the bars 142 and 144 and above the bracket member 150 is pivotally mounted a rocker bar 160 upon a transverse pin 162. At its forward end the rocker bar carries a contact screw 164 having a clamping screw 166 and being adapted to engage the upper side of the work piece. The pin 162 is provided with removable flanged bushings 168 (Fig. 6) -which are threaded into the bars 142 and 144. Itis reduced at its outer ends and surrounded by a sleeve 170 in its enlarged intermediate portion. The sleeve 170 has an opening through which passes the lower end -of a locking pin 172, threaded into the rocker bar 160 and adapted to engage a flat formed in the pin 162 beneath the opening in the sleeve 170 and serving to retain the pin against endwise displacement.

Journaled on the sleeve 170 which surrounds the pin 162, within the rocker bar 160, is a forked beam 180, the two branches of which are shown in section in Fig. 6. In'the rear end of the rocker bar 160 is provided an adjusting screw 184, provided with a. locking screw 185 and adapted to bear at its lower end upon a transverse web 182 in the forked beam 180.- The adjusting screw 184 is provided with a graduated knurled head with which cooperates a spring detent 186. The rocker bar 160 and the forked beam 180 constitute in effect. a lsingle two-part rocker, the arms of which may be relatively adjusted by turning the adjusting screw 184. vA hairpin spring 188, located between the forks of the beam 180, serves to maintain the end of the adjusting screw 184 always in engagement with the web 182. A leaf spring 189, mountedbetween the bars 142 and 144 and bearing upon the lower side 4 of the web 182 of the compound beam, serves to counterbalance the rear end thereof and maintain the contact screw 164 in engagement with the upper surface of the work piece. Bv turning the adjusting' screw 184 downwardly, the forward end of the rocker bar 160 is lowered and the Contact screw 164 brought closer to the contact screw 156, thus aii'ordin convenient means for making a final adjustment for determining the point at which the caliper acts in controlling the grinding. This construction of the caliperlng device, therefore, provides a two-part lever which carries one of the caliper points,

and by adjusting the relation of the two' parts of the lever the effective opening of the caliper may be adjusted without displacing either the latch mechanism or the tripping device.

The electric switches, which are controlled by the beam 180 as its outer end moves upwardly, will now be described. The rear end of the beam 180, which is perforated for the sake of lightness and extends into the switch casing 191, is provided with a transverse extension 192 at either side, carrying an adjustable contact screw 194 at either end each arranged to engage and lift a tripping pawl 196 pivotally mounted in the switch casing and each cooperating at its free end with a single tooth ratchet disk 198 fast on a transverse shaft 200 journaled in a frame 202 and carrying a pinion 204 at its outer end. Each pinion 204 meshes with a gear 206 on a shaft journaled at the rear of the shaft 200 and having an elongated pinion 208. Each pinion 208 meshes with a vertically disposed rack 210 formed in a vertical rod 212, each of which extends upwardly through the cover 190 of the switch casing 191 where it is provided with a knob by which it may be moved manually in one direction, that is to say, downwardly.

At its lower end each rod 212 is provided with a head 214. A sleeve 216 is mounted in line with andA below each rod 212 in vertical bearings 222 on an insulated base 224. i -Each sleeve has a plug of insulating material secured in its upper end which is adapted to make an insulated contact with the head 214 of the rod 212. At its lower end each sleeve carries-a carbon contact member 220. A.compression spring 226, surrounding the sleeve 216 between the bearing member 222 and a ring 218 on the sleeve, serves normally to elevate each rod 212 and maintain the lower flange of the sleeve in contact with the lower end of the bearing member 222.

Mounted upon the base 224 in line with and below each of the bearing members 222 is a second bearing member 230, in which is mounted a similar sleeve 232 carrying a contact piece 234 and being maintained normally in its uppermost position with its lower flange against the bottom surface of the bearing member 230. A lead wire 240 isconnected to each of the contact members 220 which are controlled by the rods 212, and lead wires 242 are connected to each of the yieldingly mounted contact members 234. The contact members 234 are yieldingly mounted so as to permit over-travel of the cooperating contact members 220and the establishment of good electrical contact when the contact members 220 are moved downwardly. i

When the operator depresses the knobs, forcing down the rods 212 to close the switch contacts, he compresses and energizes the springs 226 and also rotates the ratchet'dlsk 198 through its connected gear train. rlhe ratchet disk is latched by itsv pawl 196 and being at a pbint in the train remote from the rack 210 the locking pressure is extremely light. c

It will be understood that the calipering mechanism has a double pivot mounting which permits it to move freely up and down and toward and from the work, the plvots being the pin 138 which connects the carrier member 136 withthe bracket 132 and the of operative position. The pin 300 is ex-v tended out through the casing v191 and forms. a fulcrum for the lever 250. A link 301- pin 300 which connects the frame piece 140 Awith thecarrierinember. A lever 250 is provided for convenience in manually shifting the calipering mechanism into and out is pivotally connected at one end to the lever 250 by a bolt 302. The opposite end of the link 301 is slotted' and adapted ,to engage.

the reduced outer end of a stud 3,03 set rigidly in the bracket 132. A spring 304 1s attached at one end tothe stud 303 and. at the opposite end to a stud 305 pro]ect1ng from the link 301 and this tends normally to maintain the stud 303 in -contact with the innerend of the slot in the link 301. The lever 250 is provided with a stop projection or lug 306 adapted to Contact with the underside of the link 301 when .the position shown in Fig. 1. In -this posltlon, the portion of the lver 250 between its fulcrum on the pin 300 and the bolt 302, together with the link 301, constitute a toggle mechanism which in the position shown is locked, that is, the pivot 300 lies above'the line connecting the stud 3-03 with the bolt A'wordt as determined by the three contact' screws, further motion of the to gle being prevented by engagement of the ug 306 on the lever 250 with the under side yof the link 301.

The operation of the mechanism above discussed is as follows. Appropriate preliminary settings are first made in respect tto the position of the worm wheel 13 with respect to the feed shaft 10 to bring the mechanism is moved into operative position opposite the grinding wheel 100 and a prev liminary setting is made with the aid of a sample piece of finished work by turning the three contact screws to bring the screws 156 and 164 into engagement with that sample at diametrically opposite points and the rocker bar 180 is adjusted by the micrometer screw 184 into a position to just release the disk 198 from the pawl 196. Having made that setting, the sample work piece is removed and a piece to be ground substituted therefor. This piece, being larger, will permit the disk 198 to be locked by the pawl 196 with the switch contacts 220 and 234 closed. The rods 212 are then depressed by the operator, where they will be held by the pawls 196 closing both the switches and energizing the solenoid 66 so that lthe shifting arm 37 is moved toward the right and the clutch member 39 engaged with the high speed in-feeding clutch gear 32. The circuit, through the other pair of contact mem- The high speed in-feeding movement of the grinding wheel under the actuation of the-clutch gear 32 is a movement preliminary to. the actual rinding and brings the grindingwheel in rom the inoperative initial position which it occupies during the insertion of the work to a position in whichv it is barely in grinding contact with the work. While itfis making this movement,

the worm'wheel 49' has rotated in the direction shown by the arrow and to the position shown in Fig. 2, where the cam face 52 comes into contact with the roll and forces the lever 72 downwardly, moving the shifting arm 37 and the clutch members 36 towarda the left, overcoming the pull of the solenoid 66 and disengaging the clutch member 36 from the clutch gear 32, thereby stopping the rapid movement of the grinding wheel toward the' work. Just prior t0 the stopping of the rapid movement of the A wheel toward the work the contact segment 58 closes the circuit through the brushes 59 and 60 so that the solenoid 70 is energized and the shifting arm 42 swung toward the left, engaging the clutch member 40 with the los i slow speed in-feeding clutch gear 34. Be-

`cause of the pawl 46 serving as a driving connection between the clutch' member 40 and the shaft 26, the engagement of theJ clutch member 40 with gear 34; is ineffective until the higher speed clutch member 32 is fully disengaged. The grinding operation is, accordingly, commenced at a slow rate and under precise control. This continues until the caliper members approach each other sufficiently to trip first the. pawl 196 of the left-hand switch assembly, as seen in Fig. 8, and then in its continued movement the right-hand pawl 196. When the rst pawl is tripped, the in-eeding movement of the grinding wheel is stoppedas the spring 226 acts at once to elevate the left-hand rod tion of the cam 51 which holds the arm 72 gear 30. The arm 72 willlbe held in this` against movement in a clockwise direction.`

When, however, the further grinding action which takes place after the in-feed is stopped inthe manner described has reduced the work a slight further amount, the righthand switch assembly is tripped in the same manner as above described and the circuit of the solenoid 66 is opened and the spring 63 shifts the lever 72 and arm 37 together with the clutch 36 into engagement with the high speed out-feeding clutch gear 30, which then rapidly returns the entire mechanism to the original inoperative position. This return motion is terminated by the cam 54 engaging the cam roll on the arm 72 and moving it upward against the tension of the spring 63 to the point where the clutch member 36 is disengaged from the clutch position until the in-feeding for the next piece of work causes the worm wheel 49 to turn back and release the bell crank lever 37 to the action of the spring 63 or the pull of the solenoid 66. The operator may now throw the lever 250 upward and backward, which withdraws the entire caliper mechanism from the work. He may then insert a new piece of work and repeat the operations just described.

It should be noted that the approaching movement of the grinding wheel is caused by the closing of the electric circuit, which is, done by the hand of the operator. The stopping of the grinding feed and the separating of the wheel and the work, on the other hand, are accomplished bythe breaking of the circuits and this is effected automatically by the action of the calipering mechanism.

Many pieces of work, however, when .inserted in the grinding machine have a surface that is too rough and irregular to be at once engagedby the caliper points without risk of injury. In such cases, after placing the work in the machine, the operator may press down plungers 212, though not latching them, thereby closing the electric contacts but not yet moving the caliper into operative engagement with the work. This closing of the circuitwill start the rapid approaching movement which will, at the proper time, automatically shift, as above described, to the slow grinding feed and when the wheel has ground away the rough outer surface of the work, the operator may then swing the caliper forward into operative engagement with the workand remove his hand from the plungers 212 which will then be held by the latches 196.

It should be noted thatv as the grinding wheel is a wearable element, the position of the entire feeding mechanism will gradually change in relation to the point at which the work is ground to correct size. This relationship may be restored by means of the pinion 24 on the plunger 21 and its associated parts, rotating same through a distance as desired and relooking in another one of the series of holes 20. If the operator does not do this before an excessive amount of change of finishing position of the vari-` ous parts has taken place, 'the increased movement of the worm wheel 49 in the direction of the arrow in Fig. 2 will have brought the contacting segment 58 on insulating ring 57 to the point where it is out of contact with the brush 59, thereby opening the circuit of the solenoid and stopping the slow feed. The mechanism will now be inoperative, that is, it will not return automatically to its initial position. It would be necessary for the caliper to be withdrawn from the work, which would release the pawls 196 to open the contacts of the switches controlling both solenoids when the parts would return to their initial position. This last action described, namely the opening the circuit of solenoid 70 by means of the withdrawal of the contacting segment 58 from contact with the brush 59, is a safety action to prevent the normal and intended cycle of movement of the various parts from being exceeded.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. An electrically controlled feeding mechanism for grinding machines comprising a calipering device, a switch associated with said device and biased to an open position, a gear train connected with said' switch,

a, latch which is arranged to hold said gear train so that the switch remains closed, and a trip device restraining operation of the gear train which is arranged to be released by said calipering device.

2. An electrically controlled wheel feeding mechanism for grinding machines comprisinga calipering device, a switch biased to an open position, a gear train to operate said switch, and a trip acting on the gear',

the contact member in a closed position, and

means actuatedby said calipering device tc' trip said pawl.

4. Ina grinding machine, a work support and a grinding element relatively movable, feeding mechanism including a clutch arranged to move the two toward each other rapidly and preliminarily for a predetermined interval, a second clutch arranged to.

continue suchv approaching 'movement at slow speed, and a calipering device acting to release said second clutch to terminate said movement when the work has been reduced to a predetermined size.

5. In a grinding machine, a work support and a grinding element relatively movable, and feeding mechanism including a high speed in-feeding clutch, a low speed infeeding clutch, a high speed out-feeding clutch, and means for automatically throwing said clutches successively into and out of action. 'y

6. In a grinding machine, a work support and grinding element relativelymovable, a calipering device, and feeding mechanism including a high speed in-feeding clutch, a low speed in-feeding clutch governed in its action by said calipering device, a high speed out-feeding clutch, and means for automatically terminating its action.

7 In a grinding machine, a work support and grinding element relatively movable, a calipering device, and feeding mechanism including a high speed in-feeding clutch, mechanical timing means therefor, a low speed in-feeding clutch arranged Ato be thrown automatically into action and to be thrown out of action by said calipering device, and a high speed out-feeding clutch arranged to be thrown into action by the operation of said calipering device.

8. In a grinding machine, a .work support and grinding element relatively movable, a calipering device, and feeding mechanism including a high speedY in-feeding clutch, a low speed in-feeding clutch, automatic timing mechanism for terminating the action of the high speed clutch and initiating the action of the low speed clutch, and caliper-controlled means for terminating the action of the low speed clutch.

9. In a grinding machine, a work support and grinding element relatively movable,

a calipering device, and feeding mechanismy including a high speed in-feeding clutch, a low speed in-,feeding clutch, automatic timing mechanism for determining the sequence of operation of said high speed and 10W,l speed clutches, caliper controlled means for terminating the action of the low speed clutch, and an out-feeding clutch controlled in its action by 'said caliperJ device.

10. In a grinding machine, a work support and grinding element relatively movable, a calipering device, and feeding mechanism including a high speed in-feeding clutch, a low speed in-feeding clutch and an out-feeding clutch arranged for consecutive operation, together with caliper-controlled means for governing the operation of said two latter clutches, and means for positively preventing simultaneous engagement thereof.

11. In a grinding machine, a work supvport and Igrinding element relatively movable, feeding'tmechanism including a singlel driving sha having a high speed in-feeding clutch, a low speed in-feeding clutch and an out-feeding clutch-mounted thereon, driving connections to each clutch, automatic means for timing the action of said clutches', and means to permitl over-runningy of the low speed in-feeding clutch when the Y high speed irl-feeding clutch is in operation.

12. In a grinding machine, a work support and grinding element relatively movable, feeding mechanism including a single driving shaft' having a high speed in-feeding clutch, a -'low speed in-feeding clutch and an out-feeding clutch mounted thereon, driving connections to each clutch, a timing shaft driven by said driving shaft, and clutch timing mechanism actuated thereby.

13. In a grinding machine, a work support and grinding element relatiyely movable, a calipering device, in-feeding' Iand out-feeding clutches having a common driven member arranged to engage first with the iii-feeding clutch, cam controlled means for disengagingsaid driven clutch member from' the in-feeding clutch, and calipercontrolled means for engaging said member' with said out-feeding clutch.

14. In a grinding machine, a work support and grinding element relatively movable, a calipering device, in-feeding and out-feeding clutches having a common driven member arranged to engagevirst with the in-feeding clutch, cam controlled means for disengaging said driven clutch member from the iii-feeding clutch, a second inly disposed members each having a contact point on the Work, latch mechanism carried by one of said members, a tripping device carried by the other member, and means for adjusting the Veffective opening of the caliper without substantially displacing either the latch mechanism or the tripping device.

17. In a grinding machine, automatic feeding mechanism, an actuating system for controlling said feeding mechanism, a calipering device, a pair of spring operated controlling members located side by side and arranged `to be latched under tension by the operator, a gear train yassociated with \each controlling member and having a latch remote from its controlling member, and means operated by the calipering device for tripping one latch after another to render the controlling members successively effective in varying the action of the feeding mechanism.

18. In a grinding machine, a work support and a grinding element mounted .for relative movement, multi-speed feeding mechanism to effect a continuous relative movement therebetween, means actuated by and in timed relation to the feeding mechanism to change the speed 'of the feeding mechanism, and means including a Calipering device engageable with the work which acts to stop said feeding movement when the work has been reduced to a predetermined size.

19. In a grinding machine, a work support and a grinding element mounted for relative movement, multi-speed feeding mechanism including a rotatable feed screw and nut to effect a continuous relative movement therebetween, means actuated by and in timed relation to the rotation of the feed screw to change the speed of the feeding mechanism, and means including a calipering device engageable with the work which acts to stop said feeding movement when the Work has been reduced to a predetermined size.

20. In a grinding machine, a work support and a grinding element mounted for relative movement, multi-speed feeding mechanism for effecting a continuous relative movement therebetween, means operated by movement of the feeding mechanism tol reduce the speed of the relative movement, and means including a calipering device constructed and arranged to interrupt said relative movement when the work has been reduced to a predetermined size.

2l. In a grinding machine, a support for 22. In a grinding machine, a feed controlling calipering device comprising oppositely disposed members each having a contact point on the work, a bracket, means for slidably supporting said *calipering device for movement 4toward and away from the work, a lever interposed between said bracket and said calipering device for sliding the latter, and means associated with said lever constructed-and arranged to form a toggle mechanism to hold the calipering mechanism in operative engagement with the work.

23. A grindingv machine comprising a work support, a wheel slide, a grinding wheel rotatably mounted thereon, a feeding device to move the wheel towards and from the work, a sizing mechanism having a caliper engaging the work and an electrically controlled multi-speed power mechanism to operate said feeding device, including a switch having two sets of contact members larranged to be initially latched in a closed position by the operator and thereby cause said mechanism to start the rapid approaching movement of the grinding wheel, one set of contact members being-tripped by said calipering device when the wheel approaches, the surface of the work to produce a slow but uniform grinding feedof the wheel, and the other set being arranged to be tripped when the work has been ground to a predetermined size to cause an outward feeding movement of the grinding wheel.

24. A grinding machine comprising a work support, a .wheel slide, a" grinding 4Vwheelrotatably mounted thereon, a feeding device to move the grinding wheel towards and from the work, a sizing mechanism having a caliper engaging the work and a power operated mechanism including aV clutch to continuously drive said feeding device and an' electrically operated mechanism including a switch arranged to be initially latched in a closed position by the operator to connect the clutch and thereby start an infeed of the wheel and to be tripped by said caliperingdevice to disconnect said clutch when the work has been ground to a predetermined size to stop the infeed of the wheel.

25. A grinding machine comprising a work support. a wheel slide, a grinding wheel rotatably mounted thereon, a feeding device to move the wheel towards and from the work, a sizing mechanism having a caliper to'engage the work, and a power operated mechanism including a clutch to continuously drive said feeding device and an electrically operated mechanism including a spring actuated switch which is arranged to be latched in a closed position by the operator to connect the clutch and thereby cause said mechanism to start the infeed of the wheel and to be tripped by the calipering device when the work has been ground to a predetermined size to stop the infeed of the wheel.

26. In a grinding machine, a work support and a rotatable grinding wheel, a feeding mechanism to feed the grinding wheel towards and from the work, a .power operated gear drivingv mechanism to automatically actuate said feeding mechanism continuously, including high speed gearing to rapidly position the grinding wheel adjacent to the work, a slow speed gearing for feeding the grinding wheel to rough grind the work, ahigh speed reverse gearing to rapidly move the'grinding wheel away from the work, means actuated automatically in timed relation with the wheel movement to change the gear driving mechanism from high speed to low speed, and a caliper device engaging the work and arranged to control the power operated gear mechanism to stop the slow grinding feed and to reverse the feed so as to accurately size the work.

27. In a grinding machine, a work support and a. rotatable grinding wheel, a revcrsing feeding mechanism to feed the grinding wheel toward and from the work, a power drive mechanism to actuate said mechanism to automatically feed the grinding wheel continuously toward or from the work, first at a rapid rate to position the grinding wheel adjacent to the work, then at a slower rate to rough grind the work, then a dwell to finish grind the work and a clutch for reversing the feeding mechanism to produce al rapid and positive rearward movement of the wheel, and a caliper device engaging the work and arranged to control' said power drive mechanism so'as to accurately size the work.

28. A grinding machine comprising a work support and a rotatable grinding wheel which are movable relatively toward and from each other, a calipering device, a feeding mechanism arranged to relatively move said support and wheel, and a multispeed power mechanism forv actuating said feeding mechanism to automatically and continuously feed the grinding wheel, rst at a high speed and then ata slow speed, said low speed infeed movement being governed in its action by said caliper device, a high speed mechanism to positively actuate the feed mechanism to feed the wheel rearwardly, and means for automatically terminating its action.

29. A grinding machine comprising a work support, a grinding element movable toward and from said support, a calipering device, a feeding mechanism arranged to feed said support relatively to each other and a multi-speed power driving mechanism to actuate said feeding mechanism including a high speed infeeding mechanism, mechanically actuated mechanism for controling said means, a low speed infeeding means arranged to be thrown automatically into action and to be thrown out of action by said calipering mechanism, and a high speed outfeediiig means arranged to be thrown into -0 action by the operation of said calipering device. i

30. A feeding mechanism for grinding machines comprising a work support and a rotatable grinding wheel which are movable relatively towards and from each other, a calipering device, a feeding mechanism, and a multi-speed cluding a hig speed gearing to actuate the feeding mechanism to feed the wheel rapidly toward the work, a low speed mechanism to feed the wheel at a slower or grinding speed, automatic timing mechanism actuated by the feeding mechanism for ter-v minating the action of the high speed mechanism and initiating the action of the low speed mechanism, and a caliper controlled means for stopping the low speed mechanism.

31. A grinding machine comprising a work support, a wheel slide, a grinding wheel rotatably mounted thereon, a feeding mechanism to move thef wheel towards and from the work, a multi-speed reversible power mechanism to operate said feed device at a high and a low speed towards'the work and at a given speed away from the work, means actuated when the wheel has reached a predetermined position relativegrinding feed -of the wheel, and the other set being arranged to be actuated when the work has been ground to a further predeplower driving mechanism intermined size to actuate reversible mechanism and cause apositive outward feeding movement of the grinding wheel.

32. A grinding machine having a work 5. support, a grinding wheel movable towards and from the Work, a reversible multi-speed feed mechanism for moving the wheel toward the work at a high and a low speed and for moving the wheel away from the 10 work, a reversing mechanism including a control device for stopping, changing the speed of and reversing said feed mechanism, means acting to operate the control device and change the wheel feed from a high to a low speed when it reaches a given position relative to the work, a calipering device having a movable feeler which measures a reduction in the size of the work being ground, electrically operated means responsive to one position of said feeler while measuringthe work during the grinding operation which is connected to actuate said control device and stop the infeed of the grinding wheel when the work has reached a first predetermined size and cause the wheel to grind the work during a dwell Y period, and electrically operated means responsive toa second position of the feeler when the work has been reduced to a further predetermined size which causes the control device to reverse the wheel feed and cause the grinding wheel to withdraw from grinding contact with the work.

Signed at Worcester7 Massachusetts, this 26th day of September 1928.

WARREN F. FRASER. 

